The present invention relates generally to wheelchair lifts and, more particularly, to a flip-out ramp for a vehicle.
The Americans With Disabilities Act (ADA) requires the removal of physical obstacles to those who are physically challenged. The stated objective of this legislation has increased public awareness and concern over the requirements of the physically challenged. Consequentially, there has been more emphasis in providing systems that assist such a person to access a motor vehicle, such as a bus or mini-van.
A common manner of providing the physically challenged with access to motor vehicles is a ramp. Various ramp operating systems for motor vehicles are known in the art. Some slide out from underneath the floor of the vehicle and tilt down. Others are stowed in a vertical position and are pivoted about a hinge, while still others are supported by booms and cable assemblies. The present invention is generally directed to a xe2x80x9cflip-outxe2x80x9d type of ramp. Such a ramp is normally stowed in a horizontal position within a recess in the vehicle floor, and is pivoted upward and outwards to a downward sloping extended position. In the extended position, the ramp is adjustable to varying curb heights.
Flip-out ramps on vehicles confront a variety of technical problems. Longer ramps are desirable because the resulting slope is lower and more accessible by wheelchair-bound passengers. Longer ramps are, however, heavier and require more torque about the hinge to be reciprocated between deployed and stowed positions. To satisfy this torque requirement, such flip-out ramps use large electric motors, pneumatic devices, or hydraulic actuators to deploy and stow the ramp. Many of such systems cannot be moved manually in the event of failure of the power source unless the drive mechanism is first disengaged. Some existing flip-out ramps can be deployed or stowed manually, but they are difficult to operate because one must first overcome the resistance of the drive mechanism. Moreover, some flip-out ramps create a dangerous situation in the event of a power failure because they could deploy and crush objects in the downward path.
As noted above, many existing flip-out ramps are equipped with hydraulic, electric or pneumatic actuating devices. Such devices are obtrusive and make access to and from a vehicle difficult when the ramp is stowed. Moreover, many of such flip-out ramps have no energy storage capabilities to aid the lifting of the ramp and, thereby, preserve the life of the drive motor or even allow a smaller drive to be employed. Finally, operating systems for such flip-out ramps must have large power sources to overcome the torque placed on the hinge by the necessarily long moment arm of the flip-out ramp.
In view of the foregoing, there is a need for a compact and efficient operating system for a vehicle flip-out ramp.
In accordance with the present invention, a wheelchair ramp assembly is provided. The wheelchair ramp assembly includes a frame attachable to a vehicle having a floor, a platform coupled to a portion of the frame, a ramp having a weight, and a reciprocating mechanism disposed between the ramp and platform. The reciprocating mechanism reciprocates the ramp between a deployed position and a stowed position in response to a force. The reciprocating mechanism counterbalances the weight of the ramp during actuation of the ramp between the deployed and stowed positions to reduce the force required to reciprocate the ramp between the deployed and stowed positions.
In accordance with certain aspects of this embodiment, the reciprocating mechanism includes a torsion assembly having a torsion rod extending between a rotating end and a fixed end of the reciprocating mechanism. As the ramp is reciprocated between the deployed and stowed positions, the weight of the ramp causes the torsion rod to twist about the fixed end and resist the weight of the ramp.
In accordance with still other aspects, the reciprocating mechanism includes an actuating arm rotatably attached to the torsion assembly and first and second bearing surfaces cooperatively coupled to the ramp, wherein the first and second bearing surfaces move in a predetermined path as the ramp reciprocates between the deployed and stowed positions to contact a portion of the actuating arm and cause the torsion rod to twist.
In accordance with still yet other aspects, the wheelchair assembly includes a preload assembly coupled to the torsion assembly, wherein the preload assembly twists the torsion rod from a neutral position to assist in reciprocating the ramp between the deployed and stowed positions.